Transmission control



May 15, 1962 R. WALKER 3,034,373

TRANSMISSION CONTROL Filed Oct. 4, 1960 2 Sheets-Sheet l INVENTOR.

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ATTORNEY I United States Patent 3,034,373 TRANSMISSlON (IGNTROL Raymond Walker, Birmingham, Mich, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Oct. 4, 1950, Ser. No. 60,458 13 Qlairns. (Cl. 74-472) This invention relates to control linkages and particularly a combined control for the carburetor and transmission throttle valves.

In the operation of motor vehicles having automatic transmissions for transmitting torque from the engine to the road wheels, it has become common practice to include in the hydraulic controls for such transmissions a throttle valve. This valve acts to regulate pressure in accordance with the throttle pedal position for openin the carburetor throttle valve. The pressure varied in accordance with throttle pedal position is employed to control the action of the automatic shift valves and other control functions of automatic transmissions. Consequently, when the carburetor throttle valve is in its substantially closed position during idling, it is desirable that the throttle pressure regulated by the transmission throttle valve shall be at its minimum and likewise when the carburetor throttle valve is in substantially wide open position, the throttle pressure regulated by the transmission throttle valve is at its maximum. It is also common practice to provide an arrangement whereby the transmission can be forcibly downshifted from a high speed ratio to a lower speed ratio by movement of the accelerator or other pedal connected to the carburetor throttle valve beyond a position in which wide open carburetor throttle valve is established. Such continued movement of the accelerator pedal is for the purpose of imparting additional movement of the transmission throttle valve for certain control purposes, such as increasing the throttle valve regulated pressure to a higher downshift pressure to provide a forced downshift of the automatic shift valves without changing the carburetor throttle valve position.

Arrangements have been provided, as shown in Patent 2,823,555, patented February 18, 1958 by Casimer 3. Cislo, to provide in the linkage interconnecting the throttle pedal to both the carburetor butterfly or throttle valve and the transmission throttle valve, a pair of lever members biased to a fixed relative position by a spring so that they move together during throttle pedal movement during the full range of carburetor valve movement. When movement of the carburetor valve is stopped in the wide open position, the throttle pedal force may overcome the biasing force holding the two lever members in the same relative position and move one lever member a predetermined additional distance, to provide the downshift action for the transmission throttle valve. In this arrangement, the additional downshift movement not only requires the desired additional force to move it beyond the normal wide open carburetor throttle valve position, but also requires an increasing additional force to further compress the biasing spring to be exerted by the operator to hold the throttle pedal in the downshift position.

In accordance with this invention it is proposed to provide a detent or latch mechanism between the pair of lever members in a throttle pedal linkage connected to both the carburetor and transmission throttle valves. The latch mechanism is effective to require a higher force to move the throttle pedal beyond the normal carburetor throttle valve range of movement into the detent or forced downshift range, but requires substantially no additional force and preferably a reduced force, to hold the throttle pedal in the detent range. This is accomplished by employing a spring biased latch type of detent which, once $334,373 Patented May 15, 1962 ice it is moved out of the latching position, no longer offers resistance to throttle pedal movement.

An object of the invention is to provide in a combined control for carburetor and transmission throttle valves, a lost motion mechanism actuating boththe carburetor throttle valve and the transmission throttle valve in a normal range of movement and in a forced downshift range of movement actuating only the transmission throttle valve and having a detent mechanism resisting movement from the normal range to the forced downshift range and having no additional resistance in the forced downshift range.

Another object of the invention is to provide in a control of the foregoing character a lost motion mechanism connecting a control member to two controlled members to actuate both the controlled members in a normal range and to provide a detent feel resistance on movement of the control member from the normal range to a forced downshift range of movement in which only one of the controlled members'i-s moved without continuing the detent resistance. I

Another object of the invention is to provide in a control system of the foregoing nature a lost motion mechanism consisting of two levers, a primary lever actuated by a control member and connected to the transmission throttle valve and pivoted to a secondary lever pivoted to the frame at a point spaced from the primary lever pivot, a connection between the secondary lever and the carburetor throttle valve, and a latch mechanism between the primary and secondary levers engaged to transmit sul'ficient force from the control member to the carburetor throttle valve during normal movement which unlatches at the end of carburetor throttle valve movement in response to an additional force to permit additional movement of the primary lever to further move the transmission throttle valve control without additional force.

Another object of the invention is to provide in a control linkage a primary lever pivoted to a secondary lever which is pivoted to the frame at a point spaced from the lever pivot, a control member connected to the primary lever, one controlled member connected to the primary lever and another connected to the secondary lever, and a latch mechanism between the primary and secondary levers normally transmitting movement from the control member to both controlled members and operative in response to an increase in the resistance to movement of the second controlled member and an increase in the force applied to unlatch and then to move the primary lever relative to the secondary lever with a reduced force.

In carrying out the foregoing and other objects of the invention, for use in a power plant having an engine and automatic transmission, a throttle or fuel control for the engine, a throttle valve control for the transmission, and a carburetor or fuel control device for the engine, the controls are provided with a lost motion mechanism interconnecting the aforesaid three controls. The lost motion mechanism includes a primary lever pivoted to a secondary lever at a point spaced from the pivotal mounting of the secondary lever to the frame. The fuel control is connected to the primary lever to rotate the primary lever about its pivot on the secondary lever. The transmission throttle valvecontrol is also connected to the primary lever and at all times moves proportionally to the fuel control member movement. The carburetor throttle valve control is connected to the secondary lever and moves proportionally to the secondary lever. A latch mechanism is employed to normally hold the primary and secondary levers in the same relative position for movement as a unitary lever through the normal range of movement from zero throttle to substantially full throttle position to connect the fuel control to the fuel supply or carburetor control for proportional movement. When cle frame.

I the carburetor throttle valve reaches the full throttle position stopping further movement and the operator provides a slightly increased force, the latch mechanism will be disengaged permitting further independent movement of the primary lever and the transmission throttle valve control Without encountering any additional resistance or with reduced resistance. The latch mechanism employs as a fixed member, the pivot shaft for the secondarylever. The primmy lever is provided with a slot around the'pivot shaft to permit free movement of the primary lever relative to the shaft. A pivoted latch is also pivotally mounted on the primary lever and has a recess or detent resiliently urged into engagement with the shaft by a spring in the normal position of the two levers. When the. throttle control isto be moved to the detent position, an additional force must be applied to the throttle pedal to move the primary lever and the latchlever so that the shaft slips out'of the detent recess. Thereafter, less force is required to move the throttle pedal since the shaft merely slides along a smooth surface on the latch lever and only the normal throttle pedal reaction forces are encountered.

Further objects and features of the invention will be apparent by reference to the following detailed descriptionof the accompanying drawings illustrating a preferred embodiment of the invention.

. FTGURE l is an elevational view of the engine and transmission showing the control system. I v

FZGURE 2 is an elevational view of the lost motio mechanism. V 1

FIGURE 3 is a plan view of the lost motion mech anism. V V The invention is illustrated in FIGURE 1 in a, power plant having an engine 10' of the internal combustion type driving an automatic transmission 11 to transmit torque to the road wheels of the vehicle at variable torque ratios. The supply of fuel to the engine is controlled by a fuel supply device, such as thecarburetor 14 having a conventional carburetorbutterfly valve, not shown, controlled by a lever 16 actuated by ja rod 17., The fuel control member, such as the throttle pedal 21, is pivotally mounted in a conventional manner on thefloor '22 of the drivers compartment in, a convenient location for actuationby the drivers foot. The pedal 21 actuates one arm 23 of the bell crank lever 24 which is pivotally mounted on the support member 26 secured to the vehi- The other arm 27 of hell crank lever 24 is; pivotally connectedby pivot 28 to thethrottle control rod 2% which actuates the-lost motion mechanism 31. The transmission throttle valve control rod 32 is connected b-yfa pivot 33 to a lever '34 which actuates the .throttle'yalve control shaft 36 which extends into the transmission and througha suitable cam or linkage arrangement moves the transmission throttle valve to provide a pressure for controlling the transmission which is proportional to'throttle pedal position.

The lost motion mechanism 31 interconnecting the throttle pedal control rod 29, the carburetor butterfly valve control rod 117' and the-transmission throttle valve control rod 32 is shown in detail in FIGURES 2 and 3. The lost motion mechanism 31 consists of a primary lever 11 having an input leg *42 connected by a pivot 43 to "the throttle pedal control'rod 29 and an output leg 46 connected by a pivot 47 to the transmission throttle valve rod 32; The primary lever 41 is pivotally mounted for rotary movement about a pin 48 passing through suitable apertures in"'the opposed input and output legs 46 and through suitable apertures in the'legs 51 and 52 of the secondary lever 53; A pivot shaft 56 passes through the suitable apertures 'in the legs 51-52 of the secondary lever'to pivotally mount the secondary lever on the pivot shaft 56. The'pivot shaft 56 has a shoulder 57 and a threaded extension 58 passing through a suitable aperture I 4 The shaft 56 has a head 62 holding a secondary lever 53 in axial position on the shaft 56.. The input leg 42 of the primary lever '41 has a slot 63 in the path of shaft 56 during pivotal movementof the primary lever 41 as it pivots about pin 48 to permit relative movement between the primary and secondary lever. The output leg 46 of the primary lever =41 does not need a slot since it is displaced laterally away from shaft 56.

The shaft 56 has a reduced diameter-portion 66 to provide a cam surface for the latch lever 67. The latch lever 67 is pivoted at one end by a pivot pin 68 secured to the input'leg 42 of lever 41. The latch lever 67 has a curvedrecess 69 fitting against the cam surface 66 on shaft 56 to. lock the primary and secondary levers in the normal position shown in FIGURE 2. A coil spring rotationof the secondary lever and prevent toggle action between secondary lever and the carburetor throttle valve control rod 17 and to provide a fixed zero throttle position for both the carburetor and the throttle pedal. The aperture 74 in the support 59'and the apertures 75 in the secondary lever 53 are in alignment in a zero throttle position to positively locate the secondary lever 53 in the Zero throttle position while adjustments are made in the length of carburetor linkage, the throttle pedal linkage and the transmissionthrottle valve linkage.

The lost motion mechanism just described operated in the following manner. Assuming that the carburetor throttle member 36 and control rod 17, the throttle pedal and the control rod .19 and the transmission throttle valve and-its control rod 32 are in the position illustrated corresponding to the closed throttle position of the carburetor "whichis usually employed during engine idling. The

engine is then accelerated by moving the throttle pedal "21 counterclockwise about its pivot in a conventional 40 I mitted by the lost motion linkage 31 from the throttle pedal rod 29 tothe carburetor rod 17, is sufiiciently low so that the spring 72 will hold the latch lever 67 in the position shown with the recess 69 engaging the cam surface 66 on s-haft 56' to cause the primary and secondary lovers to rotate as a unit, to transmit the force from the throttle pedal rod 29 to the carburetor rod 17 without lost motion in the linkage 31. This force is transmitted without lost motion because the latch lever 67 engages shaft '56 to cause the primary lever '41 to rotate about the shaft S6 and transmit force from thetprirnary lever 41 through pin 48 to the secondary lever 53'which is connected to carburetor rod 17.

At the end of the normal full throttle movementrwhen the carburetor throttle valve is in the full throttleposition, the throttle valve or the actuator lever 16 engages a -stopto limit'further movement and thus resist continued in the support 59. The shaft 56 is secured in position on r the support 59 by anut 61 threaded on extension 58.

movement of the throttle pedal 21 as transmitted through the throttle pedal rod 29 to the primary lever 41. If the same light throttle pedal pressure is continued to be applied to the throttle pedal 21, no further movement of the throttle pedal and the connecting linkage and the carburetor valve rod 17 will occur. However, if the driver Wishes to obtain aforoed downshift from a higher ratio to a lower ratio in the automatic transmission, he may increase the foot pressure on the throttle pedal 21 to increase the force supplied through rod 29 to the primary lever 41. This increased counterclockwise force supplied to the primary lever 41 will tend to extend the spring 72 and slip the circular cam surface 66 out of the recess 69 in the latch lever 67. Thus at the point of transfer of the throttle pedal between movement in the normal range providing zero to full throttle and the range of movement providing forced downshift a greater force is required to move latch lever 67 to disengage the recess 69 from the cam surface 66 of shaft 56. This permits further clockwise movement of lever 41 pivoting about the pin 48 which is also pivoted to secondary lever 5-3 so that the primary lever pivots about pin 48 mounted on the second lever 53 which is now sta-.

tionary. During the range of downshift movement required to cause the transmission throttle valve to provide the increased pressure to downshift the transmission, the circular cam surface 66 on shaft 56 rides on a fiat cam surface 70 on the latch lever 67. The cam surface '70 is preferably positioned so that the force required for continued movement of the throttle pedal after the transition from the normal range of movement to the downshift range of movement is less than that required to pass through the normal to downshift transition point. It is also preferred that the force in the downshift range remain constant or decrease as opposed to the increasing force encountered when conventional biasing springs are interposed between the two levers. The cam 70 always provides suflicient resistance so the secondary lever is held in the full throttle position. The continued movement of throttle pedal rod 29 in the downshift range acts directly through the primary lever 41 to actuate the transmission throttle valve rod 32.

On return movement of the throttle pedal 21, the primary lever 41 first returns to the transition point where the spring 72 causes the latch recess 6? to re-engage circular cam surface 66 so that on continued movement from the full throttle position to the Zero throttle position, the throttle pedal again controls both the carburetor rod 17 and the transmission throttle valve rod 32 as during increasing throttle pedal positions. At the zero throttle position the portion '76 of pin 48 engages stop pad 77 on support 59 to limit return movement at the zero throttle position.

From the foregoing it will be seen that the present invention provides a combined control for carburetor and transmission throttle valves which is of the utmost simplicity but which performs efficiently the desired improved functions. Modification of the invention shown in the preferred embodiment illustrated is possible and may be made within the scope of the invention as defined in the appended claims.

I claim;

1. In a power plant, an engine having a fuel control member, a fuel supply member, means mounting said fuel supply member for movement and providing resistance at a point in the range of movement, a transmission having a torque demand control member, a support, a primary member connected to said fuel control member and said torque demand control member, a secondary member connected to said fuel supply member, means connecting said primary and secondary members to move together to transmit less than a predetermined force and operative in response to a predetermined force applied by said fuel control member and resisted by said fuel supply member to permit said fuel control member to further move said primary member to further move said torque demand control member without further increase in the force required.

2. In a power plant an engine having a fuel control member, a fuel supply member means mounting said fuel supply member for movement and providing resistance at a point in the range of movement, a transmission having a torque demand control member, a support, a primary member connected to said fuel control member and said torque demand control member, a secondary member connected to said fuel supply member, means con-,

necting said primary and secondary members to move together to transmit less than a predetermined force and operative in response to a predetermined force applied by said fuel control member and resisted by said fuel supply member to permit said fuel control member to further move said primary member to further move said torque demand control member with the same or a reduced force. e

3. In a power plant, an engine having a fuel control member, a fuel supply member, means mounting said fuel supply member for movement and providing resistance at a point in the range of movement, a transmission having a torque demand control member, -a support, a primary member connected to said fuel control member and said torque demand control member, a secondary member conected to said fuel supply member, means connecting said primary and secondary members to move together to transmit less than a predetermined force and operative in response to a predetermined force supplied by said fuel control member and resisted by said fuel supply member to permit said fuel control member to further move said primary member to further move said torque demand control member in response to a force substanti-ally less than said predetermined force.

4. In a power plant, an engine having a fuel control member, a fuel supply member, means mounting said fuel supply member for movement and providing resistance at a point in the range of movement, a transmission having a torque demand control member, a support, a primary member connected to said fuel control member and said torque demand control member, a secondary member connected to said fuel supply member, means including a spring biased latch connecting said primary and secondary members 'to move together to transmit less than a predetermined force and operative in response to a predetermined force applied by said fuel control member and resisted by said fuel supply member to disengage said latch to permit said fuel control member to further move said primary member to further move said torque demand control member with the same or a reduced force. 7

5. In a power plant, an engine having a fuel control member, a fuel supply member having a limited range of movement from idling to full throttle position, a transmission having a torque demand control member, a support, a primary member connected to said fuel control member and said torque demand control member, a secondary member connected to said fuel supply member, means connecting said primary and secondary members to move together to transmit less than a predetermined force and operative in response to a predetermined force applied by said fuel control member and resisted by said fuel supply member stopping in said full throttle position to permit said fuel control member to further move said primary member to further move said torque demand control member without further increase in the force required.

6. In a power plant, an engine having a fuel control member, a fuel supply member, means mounting said fuel supply member for movement and providing resistance at a point in the rangeof movement, a transmission having a torque demand control member, a support, a primary lever connected to said fuel control member and said torque demand control member, a secondary lever connected to said fuel supply member having a second pivot pivotally mounting said secondary lever on said support and a first pivot pivotally mounting said first lever on said secondary lever at a point spaced from said second pivot, means connecting said primary lever to said second pivot to pivot about said second pivot and operative in response to a predetermined force applied by said fuel control member and resisted by said fuel supply member to release said means to permit said fuel control member to further move said primary lever about said first pivot to further move said torque demand control member with the same or a reduced force.

7. In a power plant, an engine having a fuel control a 7 7 member, a fuel supply member, means mounting said fuel supply member for movement and providing resistance at "a point in the range of movement, a transmission having a torquev demand control member, a support, a primary lever connected to said fuel control member and said torque demand control member, a secondary lever connected to said fuel supply member having a second pivot pivotally mounting said secondary lever on said support and a first pivot pivotally mounting said first lever'on said secondary lever at a point spaced from said second pivot, latch means connecting said primary lever to said second pivot to pivot about said second pivot, and

member, a fuel supply member, means'mounting said fuel supply member for movement and providing resistance at a point in the range of movement, a transmission having a torque demand control member, a support, a primary lever connected to said fuel control member and said torque demand control member, a secondary lever "connected to said fuel supply memiberhaving a second pivot shaft pivotally mounting said secondary lever on said support and a first pivot pivotallymounting said first lever on said secondary lever at a point spaced from said second pivot, latch means including a member having a'recess biased to engage said second pivot shaft to connect said primary leverto said second pivot to pivot about said second pivot, and operative in response to a predetermined force applied bysaid fuel control member and resisted by said'fuel supply member to move said recess in said member away from said second pivot shaft to'releasesaid latch to permit said fuel control member to further move said'primary lever about said first pivot to further move said torque demand control member with the same or a reduced force.

9. In a'power plant, an engine having a fuel control' member, a fuel supply member, means mounting said fuel supply member for movement and providing resistance at a point in the range of movement, a transmissionhaving a torque demand control member, a support, a primary lever connected to said fuel control member and said torque demand control member, a secondary lever connected to said fuel supply member having a second pivot pivotally mounting said secondary lever on said support and a first pivot "pivotally mounting said first lever on said secondary lever at a 'point spaced from 'saidsecond pivot, latch means including a lever pivoted to said primary lever having a recess engaging said second pivot and biasing means to hold said lever with said re- 3 cess in engagement with said second pivot to connect said primary lever to said second pivot to pivot about said second pivot, and operative in responseto a predetermined force applied by s'aid'fuel control member and resisted by said fuel supply member to release said latch to permit said'fuel control member to. further move said primary lever about said first pivot tofurther move said torque demand control member with the same or a reduced force.

a 10. In a'poWer plant, an engine having a fuel control member, a fuel supply member, means mounting said fuel supply member for movement and providing resistance at a point in the range of movement, a transmission having a torque demand control member, a support, a primary member connected to said fuel control member and said torque demand'control member, a secondary member connected to said fuel supply member, means to pivotally mount said secondary member on a support, means including a pivot :to fpivotally supportsaidl primary member on said secondary member and a latch connecting said primaryand secondary members to move together to transmit less than a predetermined force and. operative in response to a predetermined force applied. by said fuel control member and resisted by said fuel supply member to permit said fuel control member to fur-- ther move said primary member to further move said torque demand control member with not more than said predetermined force.

11. In a linkage system, a support, a control member,

'a'first controlled member, a second controlled member,

a primary lever operatively connected to and actuated by said control member and operatively connected to said first controlled member, a secondary lever having a secondary pivot mounted on said support and having a primary pivot spaced from said secondary pivot pivotally supporting said primary lever on said secondary lever, means connecting said primary lever to rotate about said secondary pivot to cause said primary and secondary levers to rotate together to transmit less than a predetermined force to cause said control member to actuate saidfirst and second controlled members and releasing in response to said predetermined force to free said primary lever and to rotate said primary lever relative to said secondary lever by not more than said predetermined force to cause said control member to actuate said second controlled member.

12 In a linkage system, a support, a control member, a first controlled member, a second controlled member, a primary lever operatively connected to and actuated by said control member and operatively connected to said first controlled member, a secondary lever having a secondary pivot mounted on said support and having a primary pivot spaced from said secondary pivot pivotally supporting said primary lever on said secondary lover, a latch mechanism connecting said primary lever to said secondary pivot to rotate about said secondary pivot to cause said primary and secondary levers to rotate together to transmit less than a predetermined force to cause said control member to actuate said first and second controlled members and releasing in response to said predetermined force to free said primary lever and to rotate said primary. lever relativeto said secondary lever by the same or a reduced force to cause said control member to actuate said second controlled member.

13. In a linkage system, a support, a control member, a first controlled member, a second controlled member, a primary lever operatively connected to and actuated by said control member and operatively connected to said first controlled member, a secondary lever having a pivot mounting said secondary lever on said support, means 'pivotally mounting said primary lever on said secondary lever including a latch mechanism connecting said primary lever to rotate about said pivot to cause said primary and secondary levers to rotate together totransmit less than a predetermined force to cause said control member to actuate said first and second controlled members and releasing in response to said predetermined force to free said primary lever and to rotate said primary lever relative to said secondary lever by not more than said predetermined force to cause said control member to actuate said secondcontrolled member.

References Cited in the file of this patent UNITED STATES PATENTS 2,823,555 Cislo r Feb. 18, 1958 2,869,393 Hutchison Jan. 20, 1959 2,870,649 Zemke" Jan. 27, 1 959 

